Hypsibius multituberculatus, Pilato & Binda & Lisi, 2003

Pilato, Giovanni, Binda, Maria Grazia & Lisi, Oscar, 2003, Notes on some tardigrades from Central Africa, with the description of a new species of Hypsibiidae, Zootaxa 241 (1), pp. 1-7 : 3-6

Hypsibius multituberculatus n. sp. ( Fig. 1 , Table 1 )

Material examined: Democratic Republic of Congo: Mohanga, holotype (slide N. 4603) and 6 paratypes in moss samples ( Campylopus cfr. fragilis, Entodon sp. ); 1 specimen in a liverwort sample ( Plagiochila porelloides ).

Description of the holotype: Body length 255 m ( Fig. 1 A ); colourless; eyes present. Dorsal and lateral cuticle with many small, irregularly polygonal tubercles ( Fig.1 C ); anterior tubercles slightly larger than the others (diameter about 1.6 m). Small tubercles are also present on the legs.

Bucco­pharyngeal apparatus of Hypsibius type ( Fig. 1 B ); buccal tube rigid without ventral lamina; apophyses for the insertion of the stylet muscles in the shape of semilunar hooks, symmetrical with respect to the frontal plane. Mouth ventral without peribuccal lamellae and peribuccal papulae. Buccal tube 23.4 m long and 1.7 m wide (pt = 7.3); stylet supports inserted on the buccal tube at 64.0 % of its length; pharyngeal bulb, 23 m x 17 m, with two rod­shaped macroplacoids and septulum; microplacoid absent. First macroplacoid, with a central constriction, 4.5 m long (pt = 19.2), second, with a preterminal constriction, 3.3 m long (pt = 14.1), septulum 1.8 m (pt = 7.7); placoid + septulum row length 10.6 m (pt = 45.3); macroplacoid row length 8.1 m (pt = 34.6).

Claws of Hypsibius type ( Fig. 1 D ) well developed, with accessory points on the main branches. Base of external claws wider than that of the internal claws. Leg II­III external claws 11.3 m long (pt = 48.3), internal claws 9.1 m (pt = 38.9); the unfavorable orientation did not allow us to measure the claws of the hind legs. In a paratype of the same body size as the holotype, and having buccal tube 23.1 m long, the posterior claws on the hind legs are 14.3 m long (pt = 61.9); in another paratype, having buccal tube 25.0 m long, the anterior claws on the hind legs are 8.5 m long (pt = 34). Lunules absent; no cuticular bar is present on the first three pairs of legs; a cuticular bar, similar to that present in Hypsibius dujardini (Doyère 1840) and Hypsibius ragonesei Binda & Pilato 1985 , is present between the bases of the claws on the hind legs. Eggs not found.

The paratypes are similar to the holotype. We were able to measure only three specimens; in Table 1 the dimensions of some structures of the smallest (the holotype) and of the largest measured specimens are provided.

Etymology: multituberculatus = having many tubercles.

Remarks: Hypsibius multituberculatus differs from H. pradellii in the following features: cuticular tubercle shape; longer macroplacoids; shorter claws; presence of a cuticular bar between the bases of the claws on the hind legs.

It differs from H. ragonesei in the following characters: shape of the cuticular tubercles; septulum present; slightly shorter buccal tube; stylet supports inserted on the buccal tube in a slightly more cephalic position (pt = 62.7­63.4 in H. multituberculatus , 64.2­68.2 in H. ragonesei ); slightly shorter claws; presence of a cuticular bar between the claws on the hind legs.

Milnesium tardigradum Doyère 1840

Material examined: Democratic Republic of Congo: Mohanga : 1 specimen in a moss sample ( Entodon sp. ); Lukanga: 1 specimen in an undetermined lichen sample .

The species is considered cosmopolitan.

Figures

FIGURE 1. Hypsibius multituberculatus sp. n.; A, habitus; B, bucco­pharyngeal apparatus; C, detail of the cuticular sculpture; D, claws of the second pair of legs. (Scale bars in m).